Feedback system



March 29, 1966 R. N. QUENNEVILLE ETAL. 3,242,992

FEEDBACK SYSTEM Filed Sept. 25, 1964 United States Patent O Delaware Filed Sept. 25, 1964, Ser. No. 399,286

Claims. (Cl. 17 0-160.32)

This invention relates t o variable pitch propellers and more particularly to propeller yblade pitch change feedback mechanisms for usetherewith.

In the past, gear systems of the type shown in U.S. Paten-t Nos. 2,613,751, 2,849,072 and 2,850,103 have 'been used-for pitch change feedback mechanisms for variable pitch propellers. lSuch gear systems are heavy, difficult tofabricate and inaccurate. These gear systems were necessary in aircraft propellers because the propeller has two modes of rotation, namely, rotation as driven by the engine to provide 'propulsion and also rotation to vary propel-ler blade pitch. Feedback is desired with respect to propeller blade pitch change only and hence lpropeller prppulsive rotation m'ust' be eliminated from the total rotation signal to produce a propeller -pitch change rotation signal lfor feedback. The elimination of the propeller propulsive rotation from the total propeller rotation the purpose of the differential gear system.

It is an object of this invention to teach a pitch change feedback mechanism for use with a variable pitch propeller which'eliminates propeller propulsive rotation signal and changes a transilatory motion corresponding to propeller blade pitch change rotation into a rotary motion for pitch change feedback purposes and which is light in weight, simple in construction and eicient in operation.

It is a further object of this invention to teach a feedback mechanism for variable pitch propellers comprising concentric shafts joined by a pre-loaded ball screw.

It is still a further object of this invention to teach a feedback mechanism for a variable pitch propeller in which a rotary control signal is applied to the pitch change piston to cause translation thereof and wherein a first feedback shaft, which is restrained from rotation, translates with the pitch change piston and imparts a rotary motion to a second feedback shaft to which it is conne'cted through a pre-loaded ball screw, and which second shaft is rotatably connected to the control input to provide a feedback motion thereto.

Other objects and advantages will be apparent from the specification and claims and from the accompanying drawing which illustrates an embodiment of the invention.

The single figure drawing in this application is a crosssectiona-l showing of a variable pitch propeller utilizing our feedback mechanism.

Referring to the drawing, We see variable pitch propeller 10, which includes a plurality of propeller blades 12, each contained within propeller barrel 14 and mounted thereby for thrust creating rotation about axis 16. Propeller blades 12 are also suppored by barrel 14, through bearings 18, for pitch change rotation about axis 20. Bearings 22 and 24 support propeller barrel 1'4 for rotation about axis 16.

Pitch change or power piston 26 is connected to blades 12 through yoke 28 so that as piston 26 rotates about axis 16 with blades 12, piston 26 is supported within propeller barrel and housing 14 so that it can translate along axis 16 to cause pitch change rotation of blade 12 through the action of yoke 28. Pitch change piston 26 Patented Mar. 29, 1966 Frice is also caused to rotate `as it translates due to the action of yoke 28 as it changes the pitch of blades 12.

Pitch change piston 26 is caused to translate by hydraulic power. High pressure fluid is provided to annulus 30 by conventional means and distributed therefrom to either annulus 32 or 34 depending upon the position of distributor valve sleeve 36. Annulus 32 is connected to pressure chamber 38 while annulus 34 is connected to pressure chamber 40 such that when annulus 30 is in communication with annulus 32, pressurized fluid is being provided to pressure chamber 38 while pres-sure chamber 40 and annulus 34 are connected to drain. The reverse condition exists when annulus 30 is in communication with annulus 34. In this fashion, power piston 26 can be caused to translate in opposite directions along axis 16.

Distributor valve sleeve 36 is mounted within housing 52 so that it may both translate and rotate. An input signal is fed to sleeve 36 through rotary input shaft 54 which carries roller 56 therewith. Roller 56 is received in arcuate or helical cam slot 58 of sleeve 36 so that rotation of roller 56 may cause translation or rotation of sleeve val-ve 36. Due to this connection between input shaft 54 and sleeve 36, through roller andcams 56 and 58, the rotary action of input shaft 54, which is actuated by pilot lever 60, causes a transil-atory action in sleeve valve 36 placing hydraulic annulus 30 in-to communication with either annulus 32 or 34, depending upon whether it is desired to increase or decrease blade pitch. The lrotary motion of input shaft 54 imparts a transilatory motion to Valve 36 since shaft 72, to be described hereinafter, prevents rotation of sleeve 36.

Greater particulars `with respect to the construction of propeller 10 may be had by reference to U.S. Patent No. 3,080,928, U.S. Patent No. 3,153,454 and U.S. Patent No. 3,163,231.

To provide a feedback signal or motion to distributor valve 36, feedback mechanism 62 is provided. Feedback mechanism includes outer feedback shaft 64, which is restrained in rotation by spline connection to housing 512 at splines or key 66 and which is supported and preloaded by bearings 68 and 70 so that shaft 64 translates with power piston 26. Feedback mechanism 62 also includes inner feedback shaft 72, which is mounted for rotation but restrained in translation by bearing unit 74. Shaft 72 is connected to distributor valve 36 through gears or splines 74. Preloaded ball or helical screw 76 connects shafts 64 and 72 such that the transilatory action in shaft 64 caused by the translation of piston 26transfers a very accurate rotary motion to shaft 72, which in turn transfers this rotary motion to distributor valve 36 to provide a rotary and transi'latory feedback motion and also to re-establish the original position of sleeve 36 due to the action of gears or spline 74 and cam and roller 56 and 58.

Ball screw 76 is pre-loaded by normal ball screw practice. Shaft 64 is necessary to feedback mechanism 62 since feedback mechanism 62 must register the pitch change motion only of power piston 26 and this is the transilatory motion of piston 26. Since piston 26 also .rotates with propeller 12 due to both propulsive drive and pitch change, shaft 72 could not be directly attached to piston 26 through ball screw 76.

In this fashion, when input shaft 54 alters the position of distributor valve 36 to translate piston 26 and feedback shaft 64, his translation of piston 26 and shaft 64 acts through ball screw 76 to establish a rotation in shaft 72, which rotation is imparted in feedback fashion to distributor valve 36 to reestablish its original position.

It is to be understood that the invention is not limited to the specic embodiment herein illustrated and described but may be used in other Ways without departure from its spirit as defined by the following claims.

We claim:

1. In a variable pitch propeller, means to vary the pitchofsaidY propeller by a transilatory motion, control means to governr-saidpitch varying means, and feedback means between-said pitchvarying means andsaid control me-ans-including a lrst'shaftrestrained from rotating and connectedfto translate with said pitohvarying means, a second: shaftv restrainedfrom translating and connected to4 saidcontrol means, and a helical screw connecting said shaftsY so thattranslation ofsaidY lirst shaft causes rotation ofl saidsecondshaftto provide a feedback to said control means.

21. Apparatusaocordingto claim 1 wherein said control means includesa valve sleevepositionable to control said pitch varying'means and having a c am slotthereinv and to whichA said second shaft is connected for rotation, therewithand a Yroftary inputshaft-having a roller engaging vsaid-cam slot to causesaid sleeve to translate in response to rotaryfmotion of said input shaft.

3.- Apparatusaccording to'claim 2-Wherein said second fshaft-fiseonnected-to said valvesleeve by teeth.

4. Apparatus accordingfto claim 3-wherein said-shafts are concentric.

5; In a -variablefpitch propeller having an axis, propeller blades mountedfor rotation aboutsaid, axis and forpitch changey rotation, a power piston mounted to ro'- tate withsaid propeller blades and to translate with 'respect thereto, meansconnecting said piston to said blades so that translation ot said piston causes pitch 4 change rotation of .said blades, a hydraulic pressure system connected to cause said'piston to ytranslatefcon-trol means for said press-ure system including a valve sleeve mounted for rotation and translation, input'signal means including a cam and roller` to translate said sleeve to contro-1 position, and.` feedback means. between said piston' and said sleeve including ar first shaft restrained, from rotation andconnectedto-said piston togtranslate therewith, al second shaftv concentric- ,V with l said mrst,i s aaft; and restrained from translation and connected torotatesaid valve sleeve, and. a helicalzscrew. connecting said'shafts so that blade pitch changetranslationofrsaidpiston and rst shaft causes rotation of said secondvshaft to move. said valve sleeve in feedlbaclc actions Y References'V Gited-by-the Examiner- UNITEDSTALES PATQENTS' v 1/1-934' Shepard 9.1%.-380

SAMUEL LEVINE, Primary Examiner; l l JULIUS E. WEST, Examiner. E. A. PQWELL, JR., Assistant Examiner. 

1. IN A VARIABLE PITCH PROPELLER, MEANS TO VARY THE PITCH OF SAID PROPELLER BY A TRANSILATORY MOTION, CONTROL MEANS TO GOVERN SAID PITCH VARYING MEANS, AND FEEDBACK MEANS BETWEEN SAID PITCH VARYING MEANS AND SAID CONTROL MEANS INCLUDING A FIRST SHAFT RESTRAINED FROM ROTATING AND CONNECTED TO TRANSLATE WITH SAID PITCH VARYING MEANS, A SECOND SHAFT RESTRAINED FROM TRANSLATING AND CONNECTED TO SAID CONTROL MEANS, AND A HELICAL SCREW CONNECTING SAID SHAFTS SO THAT TRANSLATION OF SAID FIRST SHAFT CAUSES ROTATION OF SAID SECOND SHAFT TO PROVIDE A FEEDBACK TO SAID CONTROL MEANS. 